Make goma work for the GN build on linux.

build/toolchain/linux/BUILD.gn

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/sysroot.gni")
 import("//build/toolchain/clang.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 import("//build/toolchain/goma.gni")
 
+if (use_goma) {
+  goma_prefix = "$goma_dir/gomacc "
+} else {
+  goma_prefix = ""
+}
+
 gcc_toolchain("arm") {
-  cc = "arm-linux-gnueabi-gcc"
-  cxx = "arm-linux-gnueabi-g++"
+  cc = "${goma_prefix}arm-linux-gnueabi-gcc"
+  cxx = "${goma_prefix}arm-linux-gnueabi-g++"

[Dirk Pranke, 2014/07/17 01:18:27]

this seemed like the safest and clearest approach to me, but perhaps you might
have other ideas. 

+
   ar = "arm-linux-gnueabi-ar"
   ld = cxx
 
   toolchain_cpu_arch = "arm"
   toolchain_os = "linux"
   is_clang = false
 }
 
 gcc_toolchain("clang_x86") {
   if (use_clang_type_profiler) {
     prefix = rebase_path("//third_party/llvm-allocated-type/Linux_ia32/bin",
                          root_build_dir)
   } else {
     prefix = rebase_path("//third_party/llvm-build/Release+Asserts/bin",
                          root_build_dir)
   }
-  cc = "$prefix/clang"
-  cxx = "$prefix/clang++"
+  cc = "${goma_prefix}$prefix/clang"
+  cxx = "${goma_prefix}$prefix/clang++"
 
   ar = "ar"
   ld = cxx
 
   toolchain_cpu_arch = "x86"
   toolchain_os = "linux"
   is_clang = true
 }
 
 gcc_toolchain("x86") {
-  cc = "gcc"
-  cxx = "g++"
+  cc = "${goma_prefix}gcc"
+  cxx = "$goma_prefix}g++"
 
   ar = "ar"
   ld = cxx
 
   toolchain_cpu_arch = "x86"
   toolchain_os = "linux"
   is_clang = false
 }
 
 gcc_toolchain("clang_x64") {
   if (use_clang_type_profiler) {
     prefix = rebase_path("//third_party/llvm-allocated-type/Linux_x64/bin",
                          root_build_dir)
   } else {
     prefix = rebase_path("//third_party/llvm-build/Release+Asserts/bin",
                          root_build_dir)
   }
-  cc = "$prefix/clang"
-  cxx = "$prefix/clang++"
+  cc = "${goma_prefix}$prefix/clang"
+  cxx = "${goma_prefix}$prefix/clang++"
 
   ar = "ar"
   ld = cxx
 
   toolchain_cpu_arch = "x64"
   toolchain_os = "linux"
   is_clang = true
 }
 
 gcc_toolchain("x64") {
-  cc = "gcc"
-  cxx = "g++"
+  cc = "${goma_prefix}gcc"
+  cxx = "${goma_prefix}g++"
 
   ar = "ar"
   ld = cxx
 
   toolchain_cpu_arch = "x64"
   toolchain_os = "linux"
   is_clang = false
 }
 
 gcc_toolchain("mipsel") {

[Dirk Pranke, 2014/07/17 01:18:27]

any idea if goma supports the mipsel toolchain? 

[Nico, 2014/07/17 01:21:47]

As far as I know, no. I'm aware of a single mips bot on the internal android
waterfall (which doesn't use goma); the other mips bots are external (
http://www.rt-rk.com/mips-buildbot/builders/build_and_test_chromium_trunk_for...
) and can't use goma for that reason.

[brettw, 2014/07/17 04:37:30]

I don't touch any mips thing. The mips people contributed it and maintain it.

   cc = "mipsel-linux-gnu-gcc"
   cxx = "mipsel-linux-gnu-g++"
   ar = "mipsel-linux-gnu-ar"
   ld = cxx
 
   toolchain_cpu_arch = "mipsel"
   toolchain_os = "linux"
   is_clang = false
 }